Field of the Invention
The invention relates to a technology for changing an image size.
Description of the Background Art
When a size of an image is changed (enlarged or reduced), an interpolation process, using interpolation, has been conventionally performed to derive values of pixels of an image after a change, based on pixels of the image before the change. For example, bilinear interpolation and bicubic interpolation are among methods of the interpolation process conventionally used.
In a case where a size of an image is changed by the conventional interpolation method mentioned above, a phenomenon called jaggy occurs. In the phenomenon, edges of images are stepped in the image after the change. Jaggies generally occur in portions inclined relative to a horizontal direction.
The jaggies cause damage to outlines of images in the image and diminishes beauty of the image. Therefore, a desired technology is to reduce the jaggies caused by a change of an image size.